1. You have abstract class Machine and three sub-classes: Bulldozer, Excavator and Truck. Feel free to add some type-specific fields to these classes.

2. Each machine has the ability to start working.

3. There is MachineProducer interface created. The goal of implementation of this interface is to create a list of specific machines (Bulldozer, Excavator and Truck). You should have at least 3 implementations: BulldozerProducer, ExcavatorProducer, TruckProducer; Please parameterize your MachineProducer and replace Object in get() with the suitable option.

   public interface MachineProducer<PARAMETRIZE ME>{ ... }

4. In MachineProducer implementations your method get() should return the list of specific machines. For example:

   List<Bulldozer> get();

   or

   List<Truck> get();

   or

   List<Excavator> get();

5. There is also MachineService interface created. You need to parameterize it as well and replace Object in method signature with the right option (use PECS):

   • the method getAll(Class type) produces the list of machines based on the input param.
   • the method fill(List<Object> machines, Object value) fills the machines list with passed value.
   • the method startWorking() should be able to accept a list containing any Machine.

When you parameterize interface MachineService keep in mind that we want to restrict types that can be used with it.

Not allow:
MachineServiceImpl implements MachineService<Dog>
Allow:
MachineServiceImpl implements MachineService<Truck>
``

1. Use the created class MachineServiceImpl implementing MachineService and realize these methods:

• getAll(Class type)- based on the input class type, choose the right MachineProducer implementation and call its get() method.

For example: if (type == Bulldozer.class) - we should call the get() method from right implementation of MachineProducer (the one that will return List<Bulldozer>) and return these machines.

• fill(List<Object> machines, Object value) - update to the passed value (which can be of any Machine subtype) all elements in the machines list.

• startWorking() - call doWork on every Machine in the list.